Lead-in tape systems are commonly used to deliver signatures from a printing press to a stack. A lead-in tape system typically comprises a plurality of lead-in tape mechanisms spaced apart from one another and located side-by-side to one another to contact the signature across its width. Each lead in-tape mechanism has a lead-in tape on one side and a corresponding counter-rotating lead-in tape on the other side to form a signature passage, so that the signature is grasped on both sides and may be transported through the signature passage. Often the signature leaves the signature passage and enters a fan which receives the signature in a fan pocket. The signature is then delivered to a stack as the fan or fans rotate, as described in U.S. Pat. No. 5,112,033, herewith incorporated by reference.
The lead-in tapes typically have guide rollers and a drive roller located inside the lead-in tape for guiding and driving the tape. There are guide rollers at the bottom of the lead-in tape where the signature exits, i.e. the exit rollers.
One exit roller is typically fixed and the other exit roller spring-loaded by a single spring in the direction of the fixed roller to maintain a positive squeeze on the signature as it enters the fans. This squeeze is necessary to assist in driving the signatures into the fans to help deliver the signatures. As the signatures pass through the exit rollers, there is a head-to-tail space or gap between the individual signatures to allow the tips of successive fans to pass between the signatures. When the spring-loaded exit rollers encounter this gap in the signature stream, they close on the fixed rollers and reopen when the head of the next signature is encountered. This creates a bounce phenomena which causes high dynamic loads on the fixed rollers.
Premature failure of the bearings, tapes or other components may then occur, as well as fretting corrosion of the loaded components and slippage of exit roller levers which hold the exit roller. Replacement of these parts can be time-consuming and costly.